The application requests support for a Leica TCS SP2 AOBS Spectral Confocal Microscope. The recently introduced spectrally programmable Leica AOBS technology allows a filter-free operation, which increases the signal strength allowing reduced photobleaching and longer cell lifetimes. The microscope will be a shared facility used by members of the Departments of Microbiology (4 major and 1 minor users) and Biochemistry (3 major and 2 minor users) at New York University School of Medicine (NYU SOM). Between them, the users have 18 NIH grants. The proposed studies of these investigators primarily characterize the components of signaling pathways that regulate cell growth in normal and virally-infected or stressed cells. These projects involve the determination of sub-cellular localization of proteins in living and fixed cells, and analysis in living cells of nucleocytoplasmic shuttling using FRAP and interactions of multiple protein factors using FRET. The projects of the major users include studies of: i) transcriptional control of lytic and latent gene expression in herpesviruses (Wilson), ii) modulation of mRNA translation by Us11 in herpesvirus-infected cells (Mohr), iii) maintenance of a non-replicating Hepatitis B virus DNA episome in the infected cell nucleus (Schneider), iv) characterization of a novel mechanism for regulating p53 stability through a nucleolin-p53 interaction (Borowiec), v) the mechanism of retinal degeneration caused by defects in RP2, a causative factor in retinitis pigmentosa (Cowan), vi) localization of glucocorticoid receptor phosphorylation isoforms (Garabedian), and vii) trafficking of K+ channel proteins of the Kv4 subfamily and the dynamics of their interactions with associated proteins (Rudy). Significant progress towards these studies is currently prevented because confocal facilities at NYU SOM are heavily over-subscribed and access is severely limited. The success of these NIH-supported projects therefore requires full-time access to a high-resolution confocal microscope. As additional benefits, the instrument will enhance the training of students and postdoctoral fellows in the two departments, and provide increased synergy between user groups that will generate new research directions. The Department chairs and user groups have committed sufficient funds for instrument maintenance and training. [unreadable] [unreadable]